The USS Lincoln aircraft carrier strike group and a fleet of Air Force bombers have been in the Middle East along with anti-missile missiles and a Marine expeditionary force to deter Iranian action and guard U.S. allies. F/A-18E Super Hornets and E-2D Advanced Hawkeyes from the Lincoln and Air Force B-52H Stratofortress aircraft conducted joint exercises in the Arabian Sea this week.

"I don't actually believe the threat has diminished ... I believe the threat is very real," said McKenzie, who met recently with the Iraqi prime minister and defense chief. He declined to go into detail on the threats Iran poses.

McKenzie also said the increased presence forced Tehran to back off a planned attack against U.S. forces in the Persian Gulf region.

"They probe for weaknesses all the time," McKenzie said. "I would say the threat has probably evolved in certain ways even as our defensive posture has changed and become more aggressive, and we certainly thank our Iraqi partners for many of the things they've done."

Friday, Iranian Foreign Ministry spokesman Abbas Mousavi warned French President Emmanuel Macron that the 2015 nuclear deal may be beyond saving. His remarks were a response to Macron's call for new negotiations to save the deal, which the United States abandoned last year.

Macron and President Donald Trump met publicly Thursday to discuss the threat from Iran. Though France remains in the pact, Macron listed four common priorities the United States and France share regarding Iran's behavior -- preventing Iran from getting a nuclear weapon, reducing Iran's ballistic activity, containing Iran's regional activity and establishing peace in the region.

Mousavi said the remarks by Macron deepens distrust among the countries still in the agreement.

"The Europeans have failed to prepare the grounds for Iran to fully benefit from the multilateral agreement," Mousavi said.

France, Germany and Britain have used a trade deal called INSTEX that allows them to continue doing business with Iran and circumvent U.S. sanctions. The three countries haven't been able to actually put that trade deal to work and instead continue tinkering with it.

"They're doing very poorly as a nation," Trump said. "They're failing as a nation. And I don't want them to fail as a nation. We can turn that around very quickly, but the sanctions have been extraordinary how powerful they've been, and other things. I understand they want to talk and if they want to talk that's fine."